1. Field of the Invention
This invention concerns a sprayable or solid biodegradable wax carrier for insect pheromones and a method for a constant-rate and continuous release of pheromones from the carrier. In particular, the invention concerns a composition comprising the pheromone formulated in a paraffin wax carrier. The composition is formulated as an aqueous paraffin emulsion or as paraffin wax granules or solids. The composition is useful for mating disruption of insect pests and dispensing other bioactive compounds.
2. Background and Related Art
In recent years there has been an increased awareness and interest in biological control of insect pests as an alternative to the use of chemical pesticides (Biological Approaches to Pest Management in California, ANR Publication 21512, University of California, Oakland, Calif., 1992). Reasons for this interest include insect resistance to traditional pesticides, public concern for the environment, food safety, and worker health. Also, while fewer new pesticides are being introduced to the market due to registration and research costs, other pesticides are being withdrawn from the market because of environmental and health concerns. This has placed farmers in the difficult position of trying to grow crops without jeopardizing yield and crop quality on one side, or environmental safety and worker health on the other side.
One method of biological control which has proven successful is the use of synthetic insect sex pheromones for pest control by mating disruption. Since much of an insect's behavior is chemically controlled, there is an opportunity to interfere with the natural chemical communication between insects as a means of controlling insect pests. (Behavior-modifying Chemicals for Insect Management, Applications of Pheromones and Other Attractants, Vol. I, R. L. Ridgway, et al, Eds., Marcel Dekker, Inc., New York, N.Y. 1990).
Pheromones are semio-chemicals, that is behavior-modifying chemicals, that act as signals to other insects of the same species. Over 1600 pheromones have been identified to date, and many of these compounds can be synthetically produced (Semio-Chemicals in Crop Protection, PJB Publications Ltd., New York, N.Y., 1992). Typically, for mating disruption, a small amount of pheromone is released from a dispenser or carrier material at a level above the concentration released by female insects. When the background level of synthetic pheromone released is above a threshold, male insects are unable to locate female insects. The male's inability to find a mate will then control future populations of the insect pest (Insect Suppression with Controlled Release Pheromone Systems, Vol. I, 3-12, Kydonieus, A. et al, Eds, CRC Press, Inc., Boca Raton, Fla., 1982).
Insect control with pheromones requires a controlled release of the target pest's sex pheromone at the appropriate time, location, and concentration to prevent males from chemically locating and mating with fertile females, and thus control future generations. In order to make mating disruption with pheromones competitive with conventional methods of insect control, efficient means of application as well as dispensing systems that release the pheromones in a constant-rate and continuous manner throughout the field or orchard are needed.
One limitation for the widespread use of mating disruption as a pest control has been a lack of a sprayable controlled-release formulation able to release pheromone over an extended period of time of at least six weeks but preferably for one crop cycle or season.
Currently available commercial pheromone dispensers are made from plastic, are not biodegradable, and must be manually placed on trees. Sprayable pheromone materials that can be applied to field crops are typically synthetic microcapsules that release the pheromone over a relatively short period of time and are difficult to stick to plant surfaces.
Attempts to provide slow release dispensers for pheromones led to development of pheromone dispensers such as microcapsules, trilaminates, capillaries, "ropes" and liquid-flowables. These dispensers release the pheromone by either evaporation from capillaries or ropes (hollow tubes), by diffusion through a polymeric dispenser, or by diffusion through a microcapsule wall.
The main disadvantages of the above described dispensers are a necessity for manual placement of traps, limitation on the dispensers application height to due workers standing on ground, and their nonbiodegradability.
Another factor that has limited the development of a satisfactory sprayable material is the need for continuous and constant-rate (i.e., zero-order) pheromone release which is needed in order to maintain a constant pheromone release above the threshold necessary for mating disruption. To date, a formulation providing such continuous and constant-rate release over the extended periods of insect mating seasons has not been described.
Thus, there is a need for a sprayable carrier that allows continuous constant-rate release of the pheromone over extended time periods.
A problem encountered with all the above-listed methods and dispensers for delivery of pheromone is the inability to provide microcapsules or formulations which adhere to the treated surfaces, and which allow constant, continuous and controllable release-rate over 2 to 6 month periods.
It would, therefore, be advantageous to provide a carrier for the delivery of the pheromone to the treated surface and allow and assure the pheromone's release in a predetermined continuous and constant-rate during mating periods.
It is, therefore, a primary objective of this invention to develop a sprayable or solid biodegradable carrier material which will release pheromones over extended periods of time and disrupt insect mating.
All patents, patent applications and publications cited herein are hereby incorporated by reference.